AP Bio enzymes

Which of the following is a statement of the first law of thermodynamics? a. Energy cannot be created or destroyed. b. The entropy of the universe is decreasing. c. The entropy of the universe is constant. d. Kinetic energy is stored energy that results from the specific arrangement of matter. e. Energy cannot be transferred or transformed.

A. Energy cannot be created or destroyed

Which of the following is (are) true for anabolic pathways? a. They do not depend on enzymes. b. They are usually highly spontaneous chemical reactions. c. They consume energy to build up polymers from monomers. d. They release energy as they degrade polymers to monomers.

C They consume energy to build up polymers from monomers

Which of the following is an example of potential rather than kinetic energy? a. a boy mowing grass b. water rushing over Niagara Falls c. a firefly using light flashes to attract a mate d. a food molecule made up of energy-rich macromolecules e. an insect foraging for food

D. a food molecule made up of energy-rich macromolecules

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? a. catalysis b. metabolism c. anabolism d. dehydration e. catabolism

E. Catabolism

Which of the following statements is (are) true about enzyme-catalyzed reactions? a. The reaction is faster than the same reaction in the absence of the enzyme. b. The free energy change of the reaction is opposite from the reaction in the absence of the enzyme. c. The reaction always goes in the direction toward chemical equilibrium. d. A and B only e. A, B, and C

a. The reaction is faster than the same reaction in the absence of the enzyme.

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a delta G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the delta G for the new reaction? a. -40 kcal/mol b. -20 kcal/mol c. 0 kcal/mol d. +20 kcal/mol e. +40 kcal/mol

b. -20 kcal/mol

Which of the following statements regarding enzymes is true? a. Enzymes decrease the free energy change of a reaction. b. Enzymes increase the rate of a reaction. c. Enzymes change the direction of chemical reactions. d. Enzymes are permanently altered by the reactions they catalyze. e. Enzymes prevent changes in substrate concentrations.

b. Enzymes increase the rate of a reaction.

Why is ATP an important molecule in metabolism? a. Its hydrolysis provides an input of free energy for exergonic reactions. b. It provides energy coupling between exergonic and endergonic reactions. c. Its terminal phosphate group contains a strong covalent bond that when hydrolyzed releases free energy. d. Its terminal phosphate bond has higher energy than the other two e. A, B, C, and D

b. It provides energy coupling between exergonic and endergonic reactions.

Which of the following is true for all exergonic reactions? a. The products have more total energy than the reactants. b. The reaction proceeds with a net release of free energy. c. Some reactants will be converted to products. d. A net input of energy from the surroundings is required for the reactions to proceed. e. The reactions are nonspontaneous.

b. The reaction proceeds with a net release of free energy.

Which of the following statements is true concerning catabolic pathways? a. They combine molecules into more energy-rich molecules. b. They are usually coupled with anabolic pathways to which they supply energy in the form of ATP. c. They are endergonic. d. They are spontaneous and do not need enzyme catalysis. e. They build up complex molecules such as protein from simpler compounds.

b. They are usually coupled with anabolic pathways to which they supply energy in the form of ATP.

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's a. entropy. b. activation energy. c. endothermic level. d. heat content. e. free-energy content.

b. activation energy.

Which of the following is likely to lead to an increase in the concentration of ATP in a cell? a. an increase in a cell's anabolic activity b. an increase in a cell's catabolic activity c. an increased influx of cofactor molecules d. an increased amino acid concentration e. the cell's increased transport of materials to the environment

b. an increase in a cell's catabolic activity

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? a. by binding at the active site of the enzyme b. by changing the shape of an enzyme c. by changing the free energy change of the reaction d. by acting as a coenzyme for the reaction e. by decreasing the activation energy of the reaction

b. by changing the shape of an enzyme

Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity? a. cessation of all enzyme formation b. compartmentalization of enzymes into defined organelles c. exporting enzymes out of the cell d. connecting enzymes into large aggregates e. hydrophobic interactions

b. compartmentalization of enzymes into defined organelles

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as a. metabolic inhibition. b. feedback inhibition. c. allosteric inhibition. d. noncooperative inhibition. e. reversible inhibition.

b. feedback inhibition.

The active site of an enzyme is the region that a. binds allosteric regulators of the enzyme. b. is involved in the catalytic reaction of the enzyme. c. binds the products of the catalytic reaction. d. is inhibited by the presence of a coenzyme or a cofactor.

b. is involved in the catalytic reaction of the enzyme

What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways? a. feedback regulation b. bioenergetics c. energy coupling d. entropy e. cooperativity

c. energy coupling

Which of the following statements describes enzyme cooperativity? a. A multi-enzyme complex contains all the enzymes of a metabolic pathway. b. A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway. c. A substrate molecule bound to an active site affects the active site of several subunits. d. Several substrate molecules can be catalyzed by the same enzyme. e. A substrate binds to an active site and inhibits cooperation between enzymes in a pathway.

c. A substrate molecule bound to an active site affects the active site of several subunits.

Which of the following is most similar in structure to ATP? a. an anabolic steroid b. a DNA helix c. an RNA nucleotide d. an amino acid with three phosphate groups attached e. a phospholipid

c. an RNA nucleotide

Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in a. bringing glucose and fructose together to form sucrose. b. the release of water from sucrose as the bond between glucose and fructose is broken. c. breaking the bond between glucose and fructose and forming new bonds from the atoms of water. d. production of water from the sugar as bonds are broken between the glucose monomers. e. utilization of water as a covalent bond is formed between glucose and fructose to form sucrase.

c. breaking the bond between glucose and fructose and forming new bonds from the atoms of water.

When you have a severe fever, what may be a grave consequence if this is not controlled? a. destruction of your enzymes' primary structure b. removal of amine groups from your proteins c. change in the folding of enzymes d. removal of the amino acids in active sites e. binding of enzymes to inappropriate substrates

c. change in the folding of enzymes

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? a. denaturization of the enzyme b. allosteric inhibition c. competitive inhibition d. saturation of the enzyme activity e. insufficient cofactors

c. competitive inhibition

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because a. the starch solution has less free energy than the sugar solution. b. the hydrolysis of starch to sugar is endergonic. c. the activation energy barrier for this reaction cannot be surmounted. d. starch cannot be hydrolyzed in the presence of so much water. e. starch hydrolysis is nonspontaneous.

c. the activation energy barrier for this reaction cannot be surmounted.

Some bacteria are metabolically active in hot springs because a. they are able to maintain a cooler internal temperature. b. high temperatures make catalysis unnecessary. c. their enzymes have high optimal temperatures. d. their enzymes are completely insensitive to temperature. e. they use molecules other than proteins or RNAs as their main catalysts.

c. their enzymes have high optimal temperatures.

How can one increase the rate of a chemical reaction? a. Increase the activation energy needed. b. Cool the reactants. c. Decrease the concentration of the reactants. d. Add a catalyst. e. Increase the entropy of the reactants

d. Add a catalyst.

Which of the following is true of enzymes? a. Enzymes may require a nonprotein cofactor or ion for catalysis to take speed up more appreciably than if the enzymes act alone. b. Enzyme function is increased if the three-dimensional structure or conformation of an enzyme is altered. c. Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. d. Enzymes increase the rate of chemical reaction by lowering activation energy barriers

d. Enzymes increase the rate of chemical reaction by lowering activation energy barriers

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n) a. competitive inhibitor of the enzyme. b. noncompetitive inhibitor of the enzyme. c. allosteric activator of the enzyme. d. cofactor necessary for enzyme activity. e. coenzyme derived from a vitamin.

d. cofactor necessary for enzyme activity.

If an enzyme is added to a solution where its substrate and product are in equilibrium, what would occur? a. Additional product would be formed. b. Additional substrate would be formed. c. The reaction would change from endergonic to exergonic. d. The free energy of the system would change. e. Nothing; the reaction would stay at equilibrium.

e. Nothing; the reaction would stay at equilibrium.